Billing date is the date that shows the start of the billing period for the month. The due date shows the bill payment limit, usually 20 days from the date the bill was issued. Usually banks will advise you to pay bills 2 or 3 days before the due date to avoid delays.
This shows the smoothness and collectability of your credit. If you always pay bills regularly and fully every month, it is likely to get a smooth status. There are usually 5 types of credit quality: smooth, special attention, substandard, doubtful and loss. When your credit quality bill is already stuck, this is a sign that it will be more difficult to apply for a loan. The only step to get out is to pay off the arrears.